Sugar-free gum contains 40% less calories than regular gum. If a piece of regular gum contains 40 calories, how many calories does a piece of sugar-free gum contain?

24 calories

Step-by-step explanation:

When calculating with percentages, you need to first convert your percentage to a decimal by dividing by 100:

40/100 = 0.40

Since you want to know the amount of calories in a piece of sugar-free gum that is 40% less calories than regular gum, what you really want to know is the total amount of calories that 60% of the regular gum would produce.

1 - 0.40 = 0.60

0.60 x 40 = 24 calories

To check your answer, you can multiple 40 x 0.40 = 16 and subtract 16 from 40: 40 - 16 = 24.